Nine protocols are currently active and conducted out of the Consultation-Liaison Service-based behavioral medicine research program. These protocols examine the phenomenology and biological correlates of illness or treatment-induced mood, behavioral, and cognitive changes. The protocols address such areas as: a) the effects of previous psychiatric history on the psychiatric morbidity associated with certain diseases and their treatment; b) the psychiatric phenomenology of certain diseases and their treatment; c) the treatment response characteristics of psychiatric disorders associated with diseases or their treatment; d) biochemical factors that may serve as predictive diagnostic markers for illness or for treatment-associated mood/behavioral or cognitive syndromes; e) the effects of mood state alterations on immunologic function. Significant findings to date include demonstration of a greater than 50% prevalence of interleukin-2-induced behavioral and cognitive changes, the frequent occurrence of endogenous depression as a presenting symptom in cancer of the pancreas compared with gastric cancer, presence of excess psychiatric morbidity in patients with type-5 hyperlipoproteinemia, significant steroid-induced mood alterations in a subset of lupus patients treated with alternate day steroids and normal volunteers treated with acute high-dose steroids, and demonstration of some biological similarity between chest pain and panic disorder patients with respect to their tendency to become symptomatic during lactate infusion.